Embodiments of the present invention relate generally to a humidity sensor for high dew point processes, and more particularly, to a humidity sensor that reduces or prevents condensation from accumulating on the sensor or relevant components associated therewith.
Measuring relative humidity during high dew point processes, such as may be encountered within ovens, proofers, dryers, cooling tunnels, or the like, can be a difficult but necessary operation. For example, it can be important in commercial baking operations to monitor various baking parameters within the oven, such as temperature, air flow, heat flux, and humidity. Inconsistencies or undesirable changes in any of these parameters can result in poor quality product returning from the oven. To that end, there is equipment, for example the SCORPION® line of data sensors and loggers available from Applicant, which can be passed through a commercial baking oven with product under full load and at full temperatures, to track the above-mentioned parameters. The various sensors are generally housed in a thermal barrier or insulator block to protect sensitive electronics.
Humidity sensors constitute one type of this equipment. However, many humidity sensor chips are not rated for the extreme temperatures found in commercial ovens (e.g., 500° F. or more). Thus, the humidity sensor chips are often contained within a housing having a sample air channel formed therein, which cools the air before passing it over the humidity sensor chip. This protects the humidity sensor chip from the extreme oven temperatures, but it also becomes difficult to keep the humidity sensor chip at a temperature above the dew point found in the oven. As a result, condensation is likely to form and block the sample air channel or contact the humidity sensor chip.
One method used to address condensation involves using a heating pad to pre-heat the humidity sensor to, for example, 100-110° F. Once these temperatures are reached, the humidity sensor can be inserted into the thermal barrier and run through the oven to do a test profile. If results are good from the trial run, an actual run for humidity sensing can be performed. If there is condensation however, the data will be poor, and the humidity sensor must be heated further before doing another test. This is a labor-intensive process involving much trial-and-error, which also makes it near impossible to use a humidity sensor in commercial ovens having multiple zones with different temperatures and/or other baking parameters.
It is therefore desirable to provide a high dew point humidity sensor that can avoid developing harmful condensation during use without employing unrefined trial-and-error preheating techniques, and which can also be utilized in multi-zone high temperature equipment.